Queen Cruiseline offers nightly dinner cruises off the coast of Nanaimo and Victoria. Dinner cruise tickets sell for $80 per passenger. Queen Cruiseline's variable cost of providing the dinner is $40 per passenger, and the fixed cost of operating the vessels (depreciation, salaries, docking fees, and other expenses) is $208,000 per month. The company's relevant range extends to 17,500 monthly passengers. The break-even units are 5,200 tickets sold. If Queen Cruiseline sells 12,500 dinner cruises, compute the margin of safety

a. in units (dinner cruise tickets)

b. in sales dollars

c. as a percentage of sales